In a Dutch oven, heat oil over medium heat. Add onion, celery and garlic. Cook about 15 minutes or until vegetables are soft and beginning to brown.
Add the undrained tomatoes, roasted peppers, thyme, oregano and red pepper flakes. Season, to taste, with salt and pepper. Pour in wine and beef stock. Stir and bring to a simmer. Cook partially covered for 45 minutes, stirring occasionally. Add the clam juice and continue cooking uncovered for 5 minutes.
Stir in scallops, fish pieces and cook for 5 minutes. Add shrimp and clams. Cook for 5 more minutes. Stir in lemon juice. Ladle into bowls and sprinkle with parsley and serve with crusty bread.